The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component that can be created using a fabrication process) has decreased.
These ICs include high voltage semiconductor devices. As geometry size continues to be scaled down, it has become increasingly more difficult for existing high voltage semiconductor devices to achieve certain performance criteria. As an example, a breakdown voltage may become a performance limitation for traditional high voltage semiconductor devices. In conventional high voltage semiconductor devices, improvement in the breakdown voltage by reducing drift region doping may lead to an undesirable increase in an on-state resistance of the device.
Therefore, while existing high voltage semiconductor devices have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.